Stockholders' Equity (Tables)

3 Months Ended

Mar. 31, 2015

Equity [Abstract]

Schedule of Shares of Common Stock Reserved for Future Issuance

The following shares of common stock are reserved for future issuance at March 31, 2015:

Common stock warrants outstanding	990,031
Stock options issued and outstanding	5,194,724
Authorized for future option grants	2,734,773
Employee stock purchase plan	770,413
	9,689,941

Schedule of Assumptions Used in Black-Scholes Option-Pricing Model

The assumptions used in the Black-Scholes option-pricing model are as follows:

	Stock Option
	Three Months Ended
	March 31,
	2015			2014
Weighted average grant date fair value (per share)	$	8.58		$	17.05
Risk-free interest rate		1.7	%		1.9	%
Expected dividend yield		0.0	%		0.0	%
Expected volatility		70.4	%		78.7	%
Expected term (in years)		6.1			6.1

Summary for Allocation of Stock Compensation Expense

The following table summarizes the allocation of stock compensation expense (in thousands):

	Three Months Ended
	March 31,
	2015		2014
Cost of sales	$	324	$	364
Selling, general & administrative		2,978		3,003
Research and development		471		404
Total	$	3,773	$	3,771